Apparatus for rinsing electrophoretically-coated articles



Jan. 4, 1966 E. D. PARENT, JR

APPARATUS FOR RINSING ELECTROPHORETISALLY-COATED ARTICLES Filed Dec. 14. 1960 INVENTOR. EDWARD D. PARENT, JR.

United States Patent Filed Dec. 14, 1960, Ser. No. 75,835

2 Claims. ((ll. 134-109) This invention relates toapparatus for rinsing electrophoretically-coated articles, and more particularly to an improved apparatus for rinsing articles so coated to remove an outer non-adherent layer of coating material from an inner adherent layer.

One important application of theelectrophoretic process is the coating of electrical filaments with insulating material, such as aluminum oxide. The processinvolves the sedimentation of fine particles from a suspension thereof in an appropriate liquid. It is inherent in this process that while a cohesive layer which adheres to the coated article is formed upon the surface thereof, a non-cohesive layer which does no adhere to the surface is deposited upon the adherent layer. This phenomenon is more fully explained in my co-pending application entitled Electrophoretic Coating Apparatus, filed December 14, 1960, Serial Number 75,834, now Patent Number 3,157,588. The non-adherent layer must be removed immediately after the coating is deposited, by rinsing the article in a suitable solvent. Failure to remove the non-adherent layer. results in dissolution of the adherent layer into a non-cohesive mass similar to the non-adherent layer. The rinsing operation is carried on with a suitable solvent rinse; in the case of aluminum oxide coatings, I have found that lor 2- nitropropane, various ketones such as 3-pentanone, ether, or combinations of these solvents are effective.

Satisfactory removal of the non-adherent coating requires that the rinse liquid be flowed over the coated surface at a controlled velocity. If the velocity of the rinse liquid is too low, the non-adherent coating is not satis factorily removed; however, if the velocity is excessive, the adhesion of the inner adherent layer is adversely affected. The optimum velocity range varies with the shape of the coated article and the nature of the coating, but may be readily determined by experiment.

Additionally, it is desirable to control the direction or pattern of flow of the rinse in relation to the particular form of the article being treated. Articles having sharp bends or curves tend to accumulate heavy deposists of non-adherent coating material, and it is desirable to direct the flow of rinse throughthese regions. In the case of articles which are symmetrical in the plane of the rinsing surface, it may be desirable to afford a swirling motion about the article. With flat helically wound filaments, which are extended into a rinse liquid surface with the principal plane thereof parallel to the surface, the rinse should preferably flow radially outwardly through the coil.

Previous attempts of which I am aware to provide the desired rinsing action have included vigorous rinsing by hand, or, in the case ofautomatic coating by means of machinery which indexes articles into a rinse container, the use of a magnetic stirrer to keep the rinse in constant swirling movement. In the latter case, the accumulation of rinse-included particles dissolved from the coated articles has been made the control of the speed of the swirling motion difficult to maintain with the desired degree of accuracy; furthermore, the accumulation ofp'articles in the rinse container blocks the rinsing action on filaments having closely wound turns, in which particles become entrapped.

It is the primary object of this invention to provide an improved apparatus for rinsing electrophoretically-coated 3,227,167 Patented Jan. 4, 1966 articles, with means for affording a non-pulsing fiow of rinse liquid having a uniform velocity and directional pattern.

It is a further object of my invention to provide an improved rinsing apparatus which permits continuous use of a supply of rinse liquid by removing included particles from the rinse liquid.

It is another object of my invention to provide an im proved rinsing apparatus having means for establishing a rinse liquid surface of predetermined flow velocity and directional pattern at a uniform level for the repetitive rinsing of a series of similar coated articles.

It is still another object of my invention to provide an improved rinsing apparatus which permits the directional pattern, flow rate, and velocity of a flow of rinse liquid to be adjusted for adaptation to the rinsing of various articles.

Further objects and advantages of my invention will become apparent as the following description proceeds.

Briefly stated, in accordance with a preferred embodiment thereof, I may carry out my invention by providing a recirculating system for rinse liquid in which are arranged, in serial fiow relation, a bubbler cup for rinsing coated articles, settling basins, and a rinse liquid reservoir for maintaining a predetermined pressure head to afford a desired flow rate and velocity in the bubbler cup. Pumping means are provided to establish a recirculating flow in the system, and an overflow drain is provided in the rinse liquid reservoir to maintain a uniform pressure head.

The bubbler cup is selected from a group variously formed with one or more overflow weirs, whose shape, cross-sectional area, and circumferential location determ mine the directional pattern of rinse liquid flow through the bubbler cup. The assorted bubbler cups provide a variety of directional patterns for rinsing variously shaped coated objects; The vertical elevation of the reservoir with respect to the bubbler cup is adjustable to permit regulation of the pressure head of the rinse liquid, and thus of the rate of flow to the bubbler. The apparatus is thus adaptable to alford optimum results with various coated articles.

An arrangement of settling basins arranged for recirculation of the rinse liquid therethrough. insures thorough and effective removal of included particles of coating material from the rinse liquid.

, While the specification concludes with claims particu' larly pointing out and distinctly claiming the subject matter which I regard as my invention, it is believed that the invention will be more clearly understood from the following detailed description of a preferred embodiment thereof, referring to the accompanying drawing, in which:

FIG, 1 is a sectional view in elevation of a rinsing apparatus according to a preferred embodiment of the invention;

FIG. 2 is a pictorial view of a bubbler cup forming a portion of the apparatus;

FIG. 3 is a pictorial view of another bubbler cup, together with a double helix type of coated filament suitable for rinsing therein; and

FIG. 4 is a pictorial view of still another bubbler cup, showing a flat multiple-fold coated filament suitable for rinsing therein.

Referring to FIGS. 1 and 2, a rinsing apparatus is shown which I have found to afford uniform and effective results in the repetitive rinsing of electrophoreticallycoated articles. The apparatus generally comprises a reservoir 1, a bubbler cup 2, a first settling basin 3, a nest 4 of second settling basins, and a pump 5 for inducing a recirculating flow of rinse liquid through the elements of the system. In the embodiment illustrated, the rinsing apparatus is utilized in conjunction with a chain conveyor 6 of a conventional type arranged to dip a succession of the filaments, one of which is shown at 7, into a supply of rinse liquid 8 for rinsing a non-adherent layer of coating material therefrom. The conveyor carries a series of forceps 9 for gripping the individual filaments, and is arranged to dip the filaments successively into the rinse liquid for timed intervals. The conveyor mechanism may be of any conventional type, and further detailed description thereof is believed unnecessary.

Rinse liquid overflows continuously from the bubbler cup to a first settling basin 3, into the bottom of which the majority of coating particles removed from the filaments by the rinse settle, as shown at 10. A drain tube 12 is extended into the basin to periodically withdraw this accumulation by means of a suitable pump (not shown), or simply by siphoning action. The partially purified rinse liquid overflows to a raised drain 14 and a conduit 15 into the nest 4 of settling basins, which includes concentric basins 16, 17, and 18 successively diminishing in height outwardly to afford a successive overflow one to the other, in a slow or laminar manner. A cover 19 is placed over the basin 18 to minimize the evaporation of the volatile rinse liquid, and to prevent the ingress of foreign matter. The conduit 15 drains into the central basin 16, and overflow occurs successively to the basins 17 and 18. Further purification of the rinse liquid occurs through the setting of additional particles 20 of coating material to the bottoms of the basins.

The purified rinse liquid is removed from the outer basin 18 by means of a conduit 24 connected by a flexible tube 25 to the pump 5. While the construction of the pump is not critical to the practice to the invention, it is desirable to utilize a pump of the positive displacement type, which is at the same time not subject to clogging by the accumulation of crystalline substances remaining in the rinse liquid. The delivery rate of the pump should preferably be about twice the required bubbler delivery rate. In the embodiment shown, the pumping action is secured by the successive squeezing of the tube 25 in the direction shown by the arrow by means of a plurality of radially-extending circumferentially-spaced fingers 26, which are actuated by cam means (not shown). Pumps of this type are of well-known construction and are commercially available; no further detailed description is therefore believed to be necessary. The outlet of the flexible tube 25 is connected to a conduit 27 which conducts the pulsating flow of rinse liquid supplied by the pump to the reservoir 1.

In order to maintain a uniform pressure head for the maintenance of a uniform flow velocity in the bubbler cup 2, an overflow conduit 30 communicates with the interior of the reservoir at an outlet 31 to maintain a surface 32 of the rinse liquid at a predetermined level in spite of the pulsating flow afforded by the pump 5. The conduit 30 returns the excess rinse liquid to the settling basin 18 for recirculation. It should be noted that the pump 5 should be selected to provide a greater rate of flow than is utilized by the bubbler cup, in order to maintain the surface of the rinse liquid at the elevation of the overflow outlet 31. The reservoir is provided with a cover 33 to minimize the rate of evaporation of the volatile rinse liquid; however, a vent 34 is provided in the cover to maintain uniform atmospheric pressure on the surface of the rinse liquid as it drains.

An outlet 38 communicates with the reservoir near the bottom thereof, draining through a flexible tube 39 to a bubbler column 40 for supplying a flow of rinse to the bubbler cup 2. A pinch clamp 41 having an adjustment screw 42 is applied to the flexible tube 39 for precise control of the rate of flow of rinse to the bubbler cup.

The bubbler cup 2 is slidably received in fluid-tight relation upon the bubbler column 40. The bubbler cup is formed with one or more overflow weirs whose form and cross-sectional area control the directional pattern of the flow within the area defined by the cup. In the embodiment shown in FIGS. 1 and 2, the bubbler cup is formed with a single V-notch weir 44, which causes the rinse to form a surface 45 which flows in a more or less unidirectional manner, returning to the settling basin 3 in an overflow stream 46. This conformation is particularly adapted to rinsing a filament of the form shown in FIGS. 1 and 2, which has a sharp return bend 47 in which nonadherent coating material tends to accumulate in a thick mass during the coating process. By dipping the filament into the rinse liquid with the principal plane thereof oriented normal to the direction of rinse flow, the accumulation of non-adherent material in the return bend is found in practice to be effectively removed without injury to the adherent coating on the filament.

The velocity of the rinse flow through the bubbler cup is critical to the rinsing process, and for this reason I provide means for adjusting the height of the blubber cup relative to that of the surface 32 of the rinse liquid in the reservoir 1. These means include an arm 48 secured to the settling basin 3, in which the bubbler column 46) is secured at 49 in any suitable manner. A tongue slide 50 is secured to the arm 48, and is received in vertically slidable relation within a groove 51 formed in a supporting bracket 52. The slide 50 and the bubbler column and settling basin are supported in a vertically adjusted position by means of an adjusting screw 53 threadedly engaged in a base portion 54 of the bracket 52. The bracket is mounted on a supporting surface 55 by means of a machine screw 56. The pressure head and thus the flow rate of the rinse liquid entering the bubbler cup may be regulated by adjusting the vertical position of the bubbler column relative to that of the reservoir 1 by means of the adjusting screw 53. The flow rate is also adjustable in a convenient manner by the pinch clamp 41. While the velocity of flow of the rinse liquid is fairly critical, no specific value will be suitable for all types of filaments and coating materials; however, the optimum value may be readily obtained by experimentation, and should be such as to fully remove the nonadherent coating layer while leaving the adherent layer intact.

A variety of bubbler cups having weir formations adapted to the rinsing of variously shaped articles may be adapted to the apparatus of this invention, and two alternative configurations are shown by way of illustration in FIGS. 3 and 4. A bubbler cup having a plurality of V-notch weirs 61 spaced circumferentially thereabout is shown in FIG. 3, and may be used when it is desired to establish a radial flow pattern, as for example in rinsing a double helix filament 62. A bubbler cup 64 having two diametrically-opposed weirs 65 of relatively great width is shown in FIG. 4, and may be utilized to establish a diametrical flow pattern for rinsing articles such as are exemplified by a multiple-fold filament 66. The selection of a weir pattern for rinsing a particular article should be made in relation to the tendency of the article to accumulate large amounts of non-adherent coating in a specific pattern. It will be apparent to those skilled in the art that various weir configurations adapted to rinsing articles of miscellaneous configurations may be devised as desired. The rate of flow of rinse through the bubbler cup, and thus the flow velocity, are controlled by the pressure head established by the elevation of the reservoir above the bubbler cup.

While I have illustrated and described a preferred embodiment of my improved rinsing apparatus by way of illustration, various additional changes and modifications will occur to those skilled in the art without departing from the spirit and scope of the invention. I therefore intend to cover all such changes and modifications in the ap pended claims.

What I desire to claim and secure by Letters Patent of the United States is:

1. Apparatus for rinsing articles having a coating, said 5 apparatus comprising: an open bubbler adapted to receive liquid at one level and discharge itat a higher level; a holder for a coated article, said holder being actuable to dip said article into said bubbler until at least part of said article is below the level of the liquid in said bubbler; a reservoir for said liquid above the level of the liquid in said bubbler, said reservoir being in communication With said bubbler; a receptacle below said bubbler for the liquid overflow from said bubbler; a settling basin in communication with said receptacle for removing from said liquid overflow any coating material it may contain; a pump for forcing said liquid into said reservoir; and

means for maintaining the level of said liquid in said References Cited by the Examiner UNITED STATES PATENTS 1,148,834 8/1915 Emory 210-532 Hunt 137-577 XR Martin 134-104 Muller 210-532 XR Wilson 210167 X Zani 210-532 X Stevens 134-111 XR Van Der Molen 239-193 XR Zucker 134-111 Hightower et al. 134-111 X Assalini 210-194 X France.

ROBERT F. BURNETT, Primary Examiner.

GEORGE D. MITCHELL, HERBERT L. MARTIN,

Examiners. 

1. APPARATUS FOR RINSING ARTICLES HAVING A COATING, SAID APPARATUS COMPRISING: AN OPEN BUBBLER ADAPTED TO RECEIVE LIQUID AT ONE LEVEL AND DISCHARGE IT AT A HIGHER LEVEL; A HOLDER FOR A COATED ARTICLE, SAID HOLDER BEING ACTUABLE TO DIP SAID ARTICLE INTO SAID BUBBLER UNTIL AT LEAST PART OF SAID ARTICLE IS BELOW THE LEVEL OF THE LIQUID IN SAID BUBBLER; A RESERVOIR FOR SAID LIQUID ABOVE THE LEVEL OF THE LIQUID IN SAID BUBBLER, SAID RESERVOIR BEING IN COMMUNICATION WITH SAID BUBBLER; A RECEPTACLE BELOW SAID BUBBLER FOR THE LIQUID OVERFLOW FROM SAID BUBBLER; A SETTLING BASIN 